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Abstract:

The present invention relates to a method for assessing (analyzing) the
risk of potential adverse effects for a human patient mediated by the
administration of a CD19×CD3 bispecific antibody to said patient
comprising determining the ratio of B cells to T cells of said patient,
wherein a ratio of about 1:5 or lower is indicative for a risk of
potential adverse effects for said patient. Accordingly, the present
invention relates a method (dosage regimen) for administering a
CD19×CD3 bispecific antibody to a human patient having a B:T cell
ratio of about 1:5 or lower, comprising (a) administering a first dose of
said antibody for a first period of time; and consecutively (b)
administering a second dose of said antibody for a second period of time,
wherein said second dose exceeds said first dose.In some embodiments, a
third dose of said antibody is administered for a third period of time.
This dosage regimen can be applied in methods for treating malignant CD19
positive lymphocytes or for ameliorating and/or preventing an adverse
effect mediated by the administration of said bispecific antibody. The
present invention also relates to the use of a CD19×CD3 bispecific
antibody for the preparation of a pharmaceutical composition to be used
in a method of the present invention. A pharmaceutical package or kit
comprising a first dose and a second dose and optionally a third dose of
said antibody as defined in the methods/dosage regimen of the present
invention is disclosed as well.

Claims:

1. (canceled)

2. A method for treating malignant CD19 positive lymphocytes in a human
patient having a B:T cell ratio of about 1:5 or lower, said method
comprising: (a) administering a first dose of a CD19.times.CD3 bispecific
antibody for a first period of time to said human patient; and
consecutively (b) administering a second dose of said antibody for a
second period of time to said human patient; wherein said second dose
exceeds said first dose.

3. The method of claim 2, wherein said method ameliorates and/or prevents
an adverse effect mediated by the administration of a CD19.times.CD3
bispecific antibody to said human patient having a B:T cell ratio of
about 1:5 or lower.

8. The method of claim 2, wherein said second period of time exceeds said
first period of time.

9. The method of claim 2, wherein said first period of time exceeds 3
days.

10. The method of claim 2, wherein said first period of time is between 3
days and 10 days.

11. The method of claim 2, wherein said second period of time exceeds 18
days.

12. The method of claim 2, wherein said second period of time is between
18 days and 81 days.

13. The method of claim 2, wherein said first period of time is between 3
days and 10 days, and said second period of time is between 18 days and
81 days.

14. The method of claim 13, wherein said first period of time is 7 days
and said second period of time is 21 or 49 days.

15. The method of claim 2, wherein said first dose is between 1 and 15
μg//m2/d.

16. The method of claim 2, wherein said second dose is between 15 and 60
μg/m2/d.

17. (canceled)

18. The method of claim 2, further comprising administering after a first
and second dose for a first and second period of time a third dose of
said antibody for a third period of time.

19. The method of claim 18, wherein said third period of time exceeds
said first and second period of time, whereby said second dose exceeds
said first dose.

20. The method of claim 18, wherein said first period of time exceeds 3
days.

21. The method of claim 18, wherein said first period of time is between
3 days and 10 days.

22. The method of claim 18, wherein said second period of time exceeds 3
days.

23. The method of claim 18, wherein said second period of time is between
3 days and 10 days.

24. The method of claim 18, wherein said third period of time exceeds 8
days.

25. The method of claim 18, wherein said third period of time is between
8 days and 78 days.

26. The method of claim 18, wherein said first period of time is between
3 days and 10 days, and said second period of time is between 3 days and
10 days, and said third period of time is between 8 days and 78 days.

27. The method of claim 26, wherein said first period of time is 7 days,
said second period of time is 7 days and said third period of time is 14
or 42 days.

28. The method of claim 18, wherein said third dose exceeds said first
and second dose.

29. The method of claim 18, wherein said first dose is between 1 and 15
μg/m2/d.

30. The method of claim 18, wherein said second dose is between 1 and 15
μg/m2/d.

31. The method of claim 18, wherein said third dose is between 15 and 60
μg/m2/d.

32. The method of claim 18, wherein the route of administration of the
third dose is intravenous.

33. (canceled)

34. The method of claim 2, wherein said antibody is a bispecific single
chain antibody.

39. The method of claim 18, wherein said antibody is administered at a
first dose of 5 μg/m2/d, followed by a second dose of 15
μg/m2/d and consecutively followed by a third dose of 60
μg/m2/d.

40.-41. (canceled)

42. A kit comprising a first dose and a second dose of a pharmaceutical
composition comprising a CD19.times.CD3 bispecific antibody and a
pharmaceutical carrier.

43. The kit of claim 42, further comprising a third dose of the
pharmaceutical composition.

44. The kit of claim 42, further comprising means to administer the first
or the second dose to a patient.

45. A method for ameliorating or preventing an adverse effect mediated by
the administration of a CD19.times.CD3 bispecific antibody to a human
patient having a B:T cell ratio of about 1:5 or lower, said method
comprising: (a) determining the ratio of B cells to T cells in a sample
from said human patient; (b) identifying said human patient as having an
increased risk of potential adverse effects when the ratio of B:T cells
is about 1:5 or less; (c) administering a first dose of said antibody for
a first period of time to said patient, and consecutively; and (d)
administering a second dose of said antibody for a second period of time;
wherein said second dose exceeds said first dose.

46. The method of claim 45, wherein said adverse effect is characterized
by a neurological reaction.

48. A method for assessing the risk of potential adverse effects for a
human patient mediated by the administration of a CD19.times.CD3
bispecific antibody to said patient comprising: (a) determining the ratio
of B cells to T cells in a sample from said patient; and (b) identifying
the patient as having an increased risk of potential adverse effects when
the ratio is about 1:5 or less.

Description:

[0001] The present invention relates to a method for assessing (analyzing)
the risk of potential adverse effects for a human patient mediated by the
administration of a CD19×CD3 bispecific antibody to said patient
comprising determining the ratio of B cells to T cells of said patient,
wherein a ratio of about 1:5 or lower is indicative for a risk of
potential adverse effects for said patient. Accordingly, the present
invention relates a method (dosage regimen) for administering a
CD19×CD3 bispecific antibody to a human patient having a B:T cell
ratio of about 1:5 or lower, comprising (a) administering a first dose of
said antibody for a first period of time; and consecutively (b)
administering a second dose of said antibody for a second period of time,
wherein said second dose exceeds said first dose. In some embodiments, a
third dose of said antibody is administered for a third period of time.
This dosage regimen can be applied in methods for treating malignant CD19
positive lymphocytes or for ameliorating and/or preventing an adverse
effect mediated by the administration of said bispecific antibody. The
present invention also relates to the use of a CD19×CD3 bispecific
antibody for the preparation of a pharmaceutical composition to be used
in a method of the present invention. A pharmaceutical package or kit
comprising a first dose and a second dose and optionally a third dose of
said antibody as defined in the methods/dosage regimen of the present
invention is disclosed as well.

[0002] Antibody-based cancer therapies require a target antigen firmly
bound to the surface of cancer cells in order to be active. By binding to
the surface target, the antibody can directly deliver a deadly signal to
the cancer cell or indirectly by, for example, recruiting a cytotoxic T
cell, if it is a bispecific antibody. In an ideal treatment scenario, a
target antigen is abundantly present and accessible on every cancer cell
and is absent, shielded or much less abundant on normal cells. This
situation provides the basis for a therapeutic window in which a defined
amount of the antibody-based therapeutic effectively hits cancer cells
but spares normal cells.

[0003] Though antibodies are an effective means in treating many
disorders, in particular cancer, their administration is not necessarily
devoid of side effects. Adverse effects may cause a reversible or
irreversible change in the health status of a patient. As adverse effects
could be harmful and undesired, it is highly desirable to avoid them.
However, though it is known that a medicament can cause adverse effects,
its prescription and administration could not be avoided or is accepted,
since the medicament has an outstanding beneficial therapeutic effect or
may even be life-saving.

[0004] In clinical trials, a general distinction can be made between
adverse effects (AEs) and serious adverse effects (SAEs). Specifically,
adverse effects can be classified in 5 grades in accordance with the
Common Terminology Criteria for Adverse Events (CTCAE). Grade 1 relates
to mild AE, Grade 2 to moderate AE, Grade 3 to severe AE, Grade 4 to
life-threatening or disabling AE, while Grade 5 means death related to
AE.

[0005] An adverse effect observed in antibody therapy is the occurrence of
infusion-related side effects, such as the cytokine release syndrome
("CRS"). Other adverse side effects described to be associated with CRS
are fatigue, vomiting, tachycardia, hypertension, back pain, but also
central nervous system reactions (CNS reactions), such as seizures,
encephalopathy, cerebral edema, aseptic meningitis, and headache.

[0006] Cytokine release and neurological reactions have not only been
observed with monoclonal antibodies binding to the T cell receptor but
also with a CD19×CD3 bispecific single chain antibody binding to
the CD3 part of the T cell receptor (called Blinatumomab (MT103)).

[0007] Blinatumomab (MT103) is a lymphoma-directed, recombinant bispecific
single-chain CD19×CD3 antibody that binds to CD19 on the surface of
almost all B cells and B tumor cells and concomitantly can engage a T
cell, thereby triggering the T-cell to kill the target B cell or B tumor
cell. Blinatumomab consists of four immunoglobulin variable domains
assembled into a single polypeptide chain. Two of the variable domains
form the binding site for CD19, a cell surface antigen expressed on most
B cells and B tumor cells. The other two variable domains form the
binding site for the CD3 complex on T cells. Blinatumomab is designed to
direct the body's cytotoxic, or cell-destroying, T cells against tumor
cells, and represent a new therapeutic approach to cancer therapy.
Blinatumomab is presently in clinical trials.

[0008] As described for instance in WO 99/54440, adverse effects have been
observed in a previous study performed with Blinatumomab applied in
repeated bolus infusions to a patient with B-cell derived chronic
lymphatic leukaemia (B-CLL). As shown in FIGS. 19 and 20 of WO 99/54440,
release of TNF, IL-6 and IL-8 has been found in response to each of the
two administered 20 minute-infusions of 3 microgram and 10 microgram of
the mentioned bispecific single chain antibody, respectively, with
cytokine release after each administration. Maximal cytokine release was
observed after administration of 10 microgram of bispecific single chain
antibody. In a following clinical trial study, in which escalating doses
of the CD19×CD3 bispecific single chain antibody have been
administered to patients with B cell malignancies as bolus infusions,
adverse effects have also been observed. According to a retrospective
analysis, 7 out of 22 patients showed an early neurological reaction,
including, for example, confusion, ataxia, speech disorder, or
disorientation.

[0009] In order to try to better manage these undesired side effects, the
mode of administration of the CD19×CD3 bispecific single chain
antibody has been changed in that it has been switched over from bolus
infusion to a continuous intravenous administration of said antibody for
a longer period of time. As shown in Bargou et al. (Science 321 (2008):
974-7), doses as low as 0.005 milligrams per square meter per day
continuously administered to non-Hodgkin's lymphoma patients over four
weeks led to an elimination of lymphoma target cells in blood. Partial
and complete tumor regressions were first observed at a dose level of
0.015 milligrams/m2/d, and all seven patients treated at a dose
level of 0.06 milligrams/m2/d experienced a tumor regression (Bargou
et al., cited above). The CD19×CD3 bispecific single chain antibody
also led to clearance of tumor cells from bone marrow and liver. However,
though this (still ongoing) study established clinical proof of concept
for the therapeutic potency of the CD19×CD3 bispecific single chain
antibody format in the treatment of blood-cell derived cancer,
neurological reactions have been found in the course of the
aforementioned clinical trial. Accordingly, since Blinatumomab is a very
promising candidate medicament for treating non-Hodgkin's lymphoma (NHL),
acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL)
and/or mantle cell lymphoma, it is highly desirable to reduce or even
completely avoid undesired side-effects in the treatment of patients in
need thereof with the CD19×CD3 bispecific single chain antibody.

[0010] Evidently, it is difficult to design a CD19×CD3
antibody-based therapy, which does not cause CNS (neurological) reactions
including neurological reactions, or, to put it differently, it is
desired to provide a CD19×CD13 antibody-based medical therapies
with increased patient tolerability, i.e., reduced or even no undesired
adverse effects such as CNS reactions.

[0011] Though pharmaceutical means and methods which allow a more gradual
activation of T cell populations (see WO 2007/068354) already helped to
avoid significant adverse side effects in patients treated with the
CD19×CD3 bispecific single chain antibody, neurological reactions
could unfortunately not be prevented by these measures, in particular in
cases in which doses of more than 5 to 10 microgram per square meter per
day (i.e. 24 h) of the antibody have been administered.

[0012] Thus, the technical problem underlying the present invention was to
provide dosage regimens and methods to overcome the above problem.

[0013] The present invention addresses this need and thus provides
embodiments concerning methods as well as dosage regimens for
administering a CD19×CD3 bispecific antibody to a human patient.

[0014] These embodiments are characterized and described herein and
reflected in the claims.

[0015] It must be noted that as used herein, the singular forms "a", "an",
and "the", include plural references unless the context clearly indicates
otherwise. Thus, for example, reference to "a reagent" includes one or
more of such different reagents and reference to "the method" includes
reference to equivalent steps and methods known to those of ordinary
skill in the art that could be modified or substituted for the methods
described herein.

[0016] All publications and patents cited in this disclosure are
incorporated by reference in their entirety. To the extent the material
incorporated by reference contradicts or is inconsistent with this
specification, the specification will supersede any such material.

[0017] Unless otherwise indicated, the term "at least" preceding a series
of elements is to be understood to refer to every element in the series.
Those skilled in the art will recognize, or be able to ascertain using no
more than routine experimentation, many equivalents to the specific
embodiments of the invention described herein. Such equivalents are
intended to be encompassed by the present invention.

[0018] Throughout this specification and the claims which follow, unless
the context requires otherwise, the word "comprise", and variations such
as "comprises" and "comprising", will be understood to imply the
inclusion of a stated integer or step or group of integers or steps but
not the exclusion of any other integer or step or group of integer or
step.

[0019] Several documents are cited throughout the text of this
specification. Each of the documents cited herein (including all patents,
patent applications, scientific publications, manufacturer's
specifications, instructions, etc.), whether supra or infra, are hereby
incorporated by reference in their entirety. Nothing herein is to be
construed as an admission that the invention is not entitled to antedate
such disclosure by virtue of prior invention.

[0020] In view of the adverse events, particularly the CNS events
including neurological reactions observed with antibodies, also including
the CD19×CD3 bispecific antibody, the finding that the
CD19×CD3 bispecific single chain antibody can be administered so
that it is tolerated by the patients, if it is administered in accordance
with the dosage regimen as provided herein, is definitely remarkable.

[0021] Specifically, the present inventors observed that those patients,
to whom a CD19×CD3 bispecific antibody was administered,
encountered CNS events, if they had a B:T cell ratio of about 1:5 or
lower. Accordingly, the present invention for the first time establishes
a low B:T cell ratio as a potential high risk factor for the occurrence
of adverse effects including neurological reactions in the treatment of
malignant CD19 positive lymphocytes occurring in leukemias and lymphomas
(see Examples 2, 3 and 4).

[0022] Particularly, the inventors of the present application observed
that non-Hodgkin lymphoma (NHL) patients and acute lymphoblastic leukemia
(ALL) patients with a low B:T cell ratio in peripheral blood have an
increased risk for the development of an early neurological reaction.
This neurological reaction occurs mainly during the first day(s) of
treatment with a CD19×CD13 bispecific antibody. In particular, the
majority of the neurological reactions occurred after about 12 to 120
hours after start of treatment. These neurological reactions were
transient, fully reversible and resolved without sequelae within 3 to 72
hours after stop of the treatment.

[0023] The inventors made these unexpected observations in various
clinical trial studies using the CD19×CD3 bispecific antibody:

[0024] Looking at "short-term" (bolus) infusion trials, 7 out of 22
patients had an early neurological reaction. 6 of these 7 patients had a
low B:T cell ratio, i.e., a B:T cell ratio of about 1:5 or lower, before
treatment. Of the remaining 15 patients without neurological reaction,
only 1 patient had a low B:T cell ratio.

[0025] In an NHL clinical trial (see Bargou et al., cited above), a total
of 39 patients have been treated until August 2008. At this time point,
it has been found that all patients with a neurological reaction that led
to permanent discontinuation of the CD19×CD3 bispecific antibody
treatment had a low B:T cell ratio (i.e., a B:T cell ratio threshold
below 1:5). In particular, 5 neurological reactions have been observed in
10 patients with low B:T cell ratio (5/10), while no patient with a high
B:T cell ratio (i.e., a B:T cell ratio higher than 1:5) had a
neurological reaction that would have led to permanent discontinuation of
CD19×CD3 bispecific antibody treatment (0/29).

[0026] Thereafter, a specific cohort for patients with low B:T cell ratio,
i.e. an increased risk for early neurological reactions, was established
in order to prospectively analyze the outlined theory and to specifically
find mitigation steps for the patients at increased risk.

[0027] Since establishing these separated cohorts for high risk patients,
8 NHL patients were prospectively treated (data as of July 2009): 6
patients with low B:T cell ratio, 2 patients with high B:T cell ratio.
Again no patient with a high B:T cell ratio had a neurological reaction,
while 3 out of 6 patients with a low B:T cell ratio had a neurological
reaction, leading to discontinuation of the treatment.

[0028] In sum, 69 NHL patients, including B-cell chronic lymphocytic
leukemia (CLL) and mantle cell lymphoma (MCL), have been treated with a
CD19×CD3 bispecific antibody, both with bolus infusion and
continuous infusion:

[0029] Neurological reactions have been observed in 61% of the patients
with low B:T cell ratio. In contrast, only 2% of the patients with high
B:T cell ratio showed such adverse events (see the following examples).

[0030] In another clinical trial phase II study, 15 μg of
CD19×CD3 bispecific single chain antibody per square meter patient
body surface area per day have been administered to adult ALL patients by
continuous infusion for at least four weeks. One out of 11 ALL patients
of the high risk group having a B:T cell ratio below 1:5 showed a
neurological reaction, leading to discontinuation of the treatment. In
contrast, none of the 6 patients of the low risk group having a B:T cell
ratio higher than 1:5 showed a neurological reaction.

[0031] Moreover, in a retrospective analysis of 39 NHL patients, a
baseline B cell to T cell (B:T) ratio in peripheral blood at or below 1:5
to 1:10 was identified as the only predictive factor for the subsequent
occurrence of neurological AEs. The predictive value was then
prospectively confirmed in 8 additional patients (see Example 1).

[0032] In sum, these data establish a low B:T cell ratio, i.e., a B:T cell
ratio of about 1:5 or lower as a potential high risk factor for the
occurrence of adverse effects including neurological reactions in the
treatment of malignant CD19 positive lymphocytes occurring in leukemia
and lymphoma such as NHL, MCL, CLL and ALL in patients who are treated
with a CD19×CD3 bispecific antibody (see Examples 1 and 4).

[0033] Thus, it was an aim of the present invention to provide a method
that allows identifying patients who may be at a risk of suffering from
adverse effects when being treated with a CD19×CD3 bispecific
antibody. This method will improve drug compliance, since the
identification of patients who are at a risk of suffering from adverse
effects allows adjusting the dosage regimen of the CD19×CD3
bispecific antibody. In fact, the present inventors have applied their
finding that a B:T cell ratio of about 1:5 or lower could be a potential
risk factor for suffering from adverse effects in the treatment with a
CD19×CD3 bispecific antibody and have thus developed a dosage
regimen which is intended to prevent and/or ameliorate these adverse
effects.

[0034] Accordingly, in a first aspect the present invention provides a
method for assessing (analyzing) the risk of potential adverse effects
for a human patient mediated by the administration of a CD19×CD3
bispecific antibody to said patient comprising determining in a sample
from said patient the ratio of B cells to T cells of said patient,
wherein a ratio of about 1:5 or lower is indicative for a risk of
potential adverse effects for said patient.

[0035] "Assessing (analyzing) the risk" means that the method of the first
aspect of the present invention aims at assessing or analyzing as to
whether or not a patient has a higher or lower likelihood or probability
(i.e., an increased or decreased risk, respectively) to encounter adverse
effects. Accordingly, as is commonly known, a risk does not necessarily
mean that a patient will or will not encounter adverse effects.

[0036] In the present invention, when a patient has a B:T cell ratio of
about 1:5 or lower, said patient has (is at) an increased risk of
potential adverse effects, also including the onset of an adverse effect,
while a patient who has a B:T cell ratio higher than 1:5 does not have
(is not at) or at least has (is at) a decreased risk of potential adverse
effects, also including the onset of an adverse effect.

[0037] Accordingly, a B:T cell ratio of about 1:5 or lower is indicative
for a risk of adverse effects, while a B:T cell ratio of higher than 1:5
is not indicative for a risk of adverse effects.

[0038] Thus, the term "indicative for" when used in the context of the
method of the first aspect of the present invention means that a patient
has an increased risk of potential adverse effects if the B:T cell ratio
is about 1:5 or lower or has a decreased risk of potential adverse
effects if the B:T cell ratio is higher than 1:5.

[0039] An "adverse effect" is a harmful and undesired effect resulting
from medication in the treatment of a patient with a CD19×CD3
bispecific antibody. An adverse effect may also be termed a "side
effect". Some adverse effects only occur only when starting, increasing
or discontinuing a treatment. The inventors have observed that the
adverse effect seen in the treatment of patients with a CD19×CD3
bispecific antibody occurred after about 12 to 120 hours after the start
of the treatment and are reversible.

[0040] An adverse effect may cause medical complications. The inventors
have observed neurological reactions in patients treated with a
CD19×CD3 bispecific antibody. These neurological reaction, unless
they can be stopped or avoided, lead to non-compliance with the
CD19×CD3 bispecific antibody treatment.

[0041] However, as mentioned herein, the inventors found that the B:T cell
ratio is an indicator as to whether or not patients are at a risk of
potential adverse side effects. Specifically, a B:T cell ratio about or
lower 1:5 is an indicator that patients are at a risk of potential side
effects, while a B:T cell ratio higher than about 1:5 is an indicator
that patients have no or at least have a decreased risk of potential
side.

[0042] As mentioned before, the method of the first aspect of the present
invention is for assessing (analyzing) the risk of adverse effects and a
risk includes the assessment/analysis of likelihood or a probability.
Accordingly, the term "potential" when used in the context of adverse
effects means that--though a patient may have a B:T cell ratio of about
1:5 or lower--said patient does not necessarily have to encounter adverse
effects.

[0043] Likewise, though a patient may have a B:T cell ratio higher than
about 1:5--said patient does not necessarily have to not encounter
adverse effects. Accordingly, the term "potential" implies that the
method of the first aspect of the present invention provides predictions
as to whether or not a patient may encounter adverse effects,
but--self-explanatory as it is--cannot provide a 100% safe prediction,
since, apart from the B:T cell ratio individual factors such as sex, age,
weight, nutritional status, health status, pre-medication etc. may have
an influence as to whether or not a patient will encounter adverse
effects.

[0044] In accordance with the present invention an adverse effect is
preferably characterized by a neurological reaction (also sometimes
referred to herein as "CNS reaction" or "CNS event", for which reason
these terms can be equally used). Said neurological reaction is
preferably one or more selected from the group consisting of: confusion,
ataxia, disorientation, dysphasia, aphasia, speech impairment, cerebellar
symptoms, tremor, apraxia, seizure, grand mal convulsion, palsy, and
balance disorder.

[0045] The degree of an adverse effect can, for example, be measured in
accordance with the NCI Common Terminology Criteria for Adverse Events
v3.0 (CTCAE) (Publish Date: Dec. 12, 2003) in grades. A Grade refers to
the severity of the adverse effects. The CTCAE v3.0 displays grades 1
through 5 with unique clinical descriptions of severity for each adverse
effects:

[0046] Grade 1: mild adverse effects

[0047] Grade 2: Moderate adverse effects

[0048] Grade 3: Severe adverse effects

[0049] Grade 4: Life-threatening or disabling adverse effects.

[0050] Grade 5: Death of the patient.

[0051] A "patient" is a human individual who will be or is treated with a
CD19×CD3 bispecific antibody. In accordance with the present
invention, the patient is suspected/assumed to comprise or already
comprises malignant CD19 positive lymphocytes (in particular B cells). In
the latter case, said patient has already been diagnosed to comprise such
cells. These malignant CD19 positive lymphocytes (in particular B cells)
are present in a patient developing and/or suffering from leukemia and/or
lymphoma. In accordance with the present invention a patient is thus in
need of a treatment of malignant CD19 positive lymphocytes. Preferably, a
patient who will be or is treated with a CD19×CD3 bispecific
antibody is (or has been) diagnosed in accordance with the method of the
first aspect of the invention as described herein.

[0052] "Mediated by" when used in the context of the method of the first
aspect of the present invention means that adverse effects that a patient
may or may not encounter are caused by the administration of a
CD19×CD3 bispecific antibody. Put it differently, the
CD19×CD3 antibody is the causative agent that may cause potential
adverse effects in a patient.

[0053] The administration may be in the form of a bolus administration or
continuous administration, with continuous administration being
preferred.

[0054] In accordance with the present invention by the term "sample" is
intended any biological sample obtained from a human patient containing
polynucleotides or polypeptides or portions thereof. Biological samples
include body fluids (such as blood, serum, plasma, urine, saliva,
synovial fluid and spinal fluid) and tissue sources found to malignant
CD19 positive lymphocytes. Methods for obtaining tissue biopsies and body
fluids from patients are well known in the art. Generally, a biological
sample which includes peripheral blood mononuclear cells (PBMCs), in
particular B cells and T cells is preferred as a source.

[0055] A sample which includes peripheral blood mononuclear cells (PBMCs),
in particular B cells and T cells is preferably taken from peripheral
blood of a human patient.

[0056] Other preferred samples are whole blood, serum, plasma or synovial
fluid, with plasma or serum being most preferred. However, a sample from
peripheral blood of a human patient is particularly preferred.

[0057] A "B:T cell ratio" as used herein refers to the ratio of the number
of B cells and the number of T cells. It is preferably determined in a
sample taken from a human patient. Preferably, the sample is taken from
the peripheral blood of a human patient. The number of B or T cells, for
example, in a peripheral blood sample can be determined by any means
usually applied in the art, for example, by FACS analysis.

[0060] (a) determining the total B cell number in a sample from a patient,
preferably in a peripheral blood sample of the patient;

[0061] (b) determining the total T cell number in sample from a patient,
preferably in a peripheral blood sample of the patient;

[0062] (c) calculating the ratio of the B cell number of step (a) and the
T cell number of step (b) in order to obtain a B:T cell ratio.

[0063] Of note, a low B:T cell ratio can also be seen as high T:B ratio;
and vice versa. Accordingly, the ratios provided herein for a low B:T
cell ratio would then have to be reversed.

[0064] In contrast, patients showing a B:T cell ratio higher than about
1:5 (preferably 1:9), including a B:T cell ratio of higher than about
1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1 or
higher, have a decreased risk of suffering from potential adverse effects
upon administration of a CD19×CD3 bispecific antibody.

[0065] Accordingly, the present invention also envisages a method for
assessing (analyzing) the risk of potential adverse effects for a human
patient mediated by the administration of a CD19×CD3 bispecific
antibody to said patient comprising determining in a sample from said
patient the ratio of B cells to T cells of said patient, wherein a ratio
of higher than about 1:5 (preferably 1:9) is indicative for a decreased
risk of potential adverse effects for said patient.

[0066] Having observed that patients who have a B:T cell ratio of about
1:5 or lower are at an increased risk of potential adverse effects, the
inventors developed a concept that allows the treatment of these patients
with a CD19×CD3 bispecific antibody. Bearing this in mind, it has
been elucidated that the T cells of such high risk patients have to be
pre-adapted or partially activated by the administration of a low dose of
antibody for several days before the dose can then be escalated. So it
has been found that a significant decrease in dose given per time unit
potentially increases tolerability to said antibody in the high risk
patients. In essence, the inventors found that "adapting" a patient to a
CD19×CD3 bispecific antibody prior to the therapy with a
CD19×CD3 bispecific antibody is beneficial for avoiding undesired
adverse effect (particularly the unwanted neurological reactions) (see
Examples 6 and 7).

[0067] Accordingly, the present invention relates in a second aspect to a
method (dosage regimen) for administering a CD19×CD3 bispecific
antibody to a human patient having a B:T cell ratio of about 1:5 or
lower, comprising:

[0068] a) administering a first dose of said antibody for a first period
of time; and consecutively

[0069] (b) administering a second dose of said antibody for a second
period of time;

wherein said second dose exceeds said first dose.

[0070] It will be understood that in the context of the present invention,
the term "method" includes a "dosage regimen" to be used in a method of
the present invention.

[0071] In the context of the present invention "administration of a
CD19×CD3 bispecific antibody" or "administering a CD19×CD3
bispecific antibody" or any other grammatical form thereof means that the
CD19×CD3 antibody is in the form of a pharmaceutical composition,
optionally comprising a pharmaceutically acceptable carrier. Accordingly,
it is to be understood that a pharmaceutical composition comprising a
CD19×CD3 bispecific antibody is administered to a human patient.

[0072] The term "administering" in all of its grammatical forms means
administration of a CD19×CD3 bispecific antibody (in the form of a
pharmaceutical composition) either as the sole therapeutic agent or in
combination with another therapeutic agent.

[0073] It is thus envisaged that the pharmaceutical composition of the
present invention are employed in co-therapy approaches, i.e. in
co-administration with other medicaments or drugs, for example, other
medicaments for treating malignant CD19 positive lymphocytes in a patient
and/or any other therapeutic agent which might be beneficial in the
context of the methods of the present invention.

[0074] For example, if the methods of the invention are carried out for
the treatment of B-lineage acute lymphoblastic leukemia or aggressive
NHL, it can advantageously be combined with inthrathecal chemotherapy in
order to eliminate target B cells from the CNS. For example, the
inthratecal chemotherapy could be performed prior to the administration
of the CD19×CD3 bispecific single chain antibody according to the
methods described herein.

[0075] The administration of a pharmaceutical composition referred to
herein is preferably an intravenous administration. It follows that in
the methods of the present invention the route of administration in step
(a) and/or the route of administration in step (b) is intravenous. It may
be administered as a bolus injection or continually (continuously), with
continually being preferred.

[0076] The administration of a CD19×CD3 bispecific antibody (for
example in the form of a pharmaceutical composition) can be a bolus
injection or continually or as also sometimes used herein continuously,
with continually or continuously being preferred. A continual
administration refers to an administration which is essentially without
interruption. "Essentially without interruption" includes a continual
administration usually without an uninterrupted flow or spatial
extension.

[0077] In some embodiments, said first dose is not therapeutically active,
i.e. it is a subtherapeutic dose. Without being strictly bound, for the
purpose of the present invention a dose of 5 μg/m2/d or lower is
held to be subtherapeutic.

[0078] In a preferred embodiment of the present invention the second dose
is therapeutically active.

[0079] By "therapeutically effective amount" or "therapeutically active"
is meant a dose of a CD19×CD3 bispecific antibody that produces the
therapeutic effects for which it is administered.

[0080] The exact dose will depend on the purpose of the treatment, and
will be ascertainable by one skilled in the art using known techniques.
As is known in the art and described above, adjustments for age, body
weight, general health, sex, diet, drug interaction and the severity of
the condition may be necessary, and will be ascertainable with routine
experimentation by those skilled in the art. The therapeutic effect of
the respective methods or method steps of the present invention is
additionally detectable by all established methods and approaches which
will indicate a therapeutic effect. It is, for example, envisaged that
the therapeutic effect is detected by way of surgical resection or biopsy
of an affected tissue/organ which is subsequently analyzed by way of
immunohistochemical (IHC) or comparable immunological techniques.
Alternatively it is also envisaged that the tumor markers in the serum of
the patient (if present) are detected in order to diagnose whether the
therapeutic approach is already effective or not. Additionally or
alternatively it is also possible to evaluate the general appearance of
the respective patient (fitness, well-being, decrease of tumor-mediated
ailment etc.) which will also aid the skilled practitioner to evaluate
whether a therapeutic effect is already there. The skilled person is
aware of numerous other ways which will enable him or her to observe a
therapeutic effect of the compounds of the present invention.

[0081] In a third aspect, the present invention relates to a method for
treating malignant CD19 positive lymphocytes in a human patient having a
B:T cell ratio of about 1:5 or lower, said method comprising:

[0082] (a) administering a first dose of a CD19×CD3 bispecific
antibody for a first period of time; and consecutively

[0083] (b) administering a second dose of said antibody for a second
period of time;

[0085] "Malignant" describes lymphocytes (in particular B cells) that
contribute to a progressively worsening disease, in particular lymphoma
or leukemia and the diseases described herein. The term is most familiar
as a description of cancer, here lymphoma and leukemia and the diseases
described herein. Malignant CD19 positive lymphocytes (in particular B
cells) are not self-limited in their growth, are capable of invading into
adjacent tissues, and may be capable of spreading to distant tissues
(metastasizing). Malignant when used herein is synonymous with cancerous.

[0086] However, as "normal" (non-malignant) lymphocytes (in particular B
cells) also express CD19, it is to be expected that the CD19×CD3
bispecific antibody also binds these normal lymphocytes (in particular B
cells) and upon recruiting cytotoxic T cells (because of the second
specificity of the bispecific CD19×CD13 antibody) depletes these
normal B cells. Yet, it is expected that the population of these normal B
cells is reconstituted in the absence of the CD19×CD3 bispecific
antibody. It was observed by Leandro and co-workers that after their
depletion by an anti-CD20 antibody, B cells were reconstituted in
rheumatoid arthritis patients (Arthritis Rheum. 2006
February;54(2):613-20). As CD20, likewise CD19 is expressed on almost all
B cells, it can be expected that B cells upon depletion by the bispecific
CD19×CD3 antibody are reconstituted, too.

[0089] In a fourth aspect, the present invention relates to a method for
ameliorating and/or preventing an adverse effect mediated by the
administration of a CD19×CD3 bispecific antibody to a human patient
having a B:T cell ratio of about 1:5 or lower, said method comprising:

[0090] (a) administering a first dose of said antibody for a first period
of time, and consecutively

[0091] (b) administering a second dose of said antibody for a second
period of time;

[0093] Specifically, neurological reactions observed during the starting
phase of treatment with the CD19×CD3 bispecific antibody include
for example confusion and disorientation. "Confusion" as used herein
refers to loss of orientation which is the ability to place oneself
correctly in the world by time, location, and personal identity, and
often memory which is the ability to correctly recall previous events or
learn new material. The patients usually have difficulties to concentrate
and thinking is not only blurred and unclear but often significantly
slowed down. Patients with neurological reactions also suffer from loss
of memory. Frequently, the confusion leads to the loss of ability to
recognize people and/or places, or to tell time and the date. Feelings of
disorientation are common in confusion, and the decision-making ability
is impaired. Neurological reactions further comprise blurred speech
and/or word finding difficulties. This disorder may impair both, the
expression and understanding of language as well as reading and writing.
Besides urinary incontinence, also vertigo and dizziness may accompany
neurological reactions in some patients.

[0094] The occurrence of neurological reactions in the treatment of B cell
dependent lymphatic or leukemic malignancies with the CD19×CD3
bispecific antibody may be further influenced by the following factors:

1. Presence of Drug

[0095] The CD19×CD3 bispecific antibody retargets T cell
cytotoxicity to malignant CD19 positive lymphocytes present, for example,
in B cell lymphoma or leukemia cells. In light of this, it can be
reasonably assumed that it is the presence of CD19×CD3 bispecific
antibody in the body of a patient which is responsible for the adverse
effects. Furthermore, side effects are observed only in parts of the body
where the CD19×CD3 bispecific antibody is biologically active.
Accordingly, neurological reactions upon treatment with the
CD19×CD3 bispecific antibody are assumed to be dependent on the
presence of said antibody in the cerebrospinal fluid (CSF; liquor) of the
patient. This may be supported by the fact that the CD19×CD3
bispecific antibody as well as T cells have only been found in the CSF of
NHL patients with a low B:T cell ratio. As explained herein, this patient
population has an increased risk for the development of neurological
reactions upon antibody treatment. This finding may suggest that the
CD19×CD3 bispecific antibody is able to enter the perivascular
space dividing the blood vessels and the CNS (including the brain), in
high risk NHL and ALL patients. There, the CD19×CD3 bispecific
antibody may then engage T cells to target local B cells (either benign
or malign) which possibly leads to local cytokine release which in turn
could cause neurological reactions.

2. Drug Dose

[0096] Further, the neurological reactions seem to be dependent on the
dose of the CD19×CD3 bispecific antibody. For example, neurological
reactions have not been observed upon continuous administration of 5
μg/m2 body surface area of CD19×CD3 bispecific antibody,
but with 15 μg/m2 body surface area or more CD19×CD3
bispecific antibody in the high risk group of patients. For this reason,
as mentioned herein, a dose of less than 5 μg/d/m2 is deemed to
be subtherapeutic. The effect of the drug dose is evident from the data
shown in the appended examples. This observation may imply a dose
dependency of neurological reactions in high risk patients with low B:T
cell ratio.

[0098] In view of this, it is intriguing to hypothesize that the depletion
of e.g. the target B cell from the PVS/CNS should result in the avoidance
of neurological reactions. In fact, this is exactly what has been
observed in the mentioned phase II study in which B lineage acute
lymphoblastic leukemia (ALL) patients are being currently treated with
the CD19×CD3 bispecific antibody:

[0099] In ALL, there is generally a high incidence of leukemic lesions in
the CNS. Therefore, each of the ALL patients enrolled in the clinical
phase II study referred to herein had received standard ALL therapies in
the past, including methotrexate i.v. and/or intrathecal chemotherapy, in
order to prevent central nervous system relapses. Some of them received
in addition irradiation of the neuroaxis. The ALL patients thereafter
received a consolidation therapy, i.e. they obtained several four
week-treatment cycles of continuous administration of 15 μg/d/m2
of CD19×CD3 bispecific antibody. Only one of the thus far enrolled
17 ALL patients who have been treated with the CD19×CD3 bispecific
antibody has developed neurological reactions. This patient was one out
of 11 patients belonging to the high risk group having a B:T cell ratio
lower than 1:5. None of the six patients of the low risk group with a B:T
cell ratio higher than 1:5 showed neurological reactions. It is therefore
hypothesized that the mentioned (pre-symptomatic) central nervous system
(CNS) treatment reduced the risk of a neurological reaction in the ALL
patient in that the B lymphocytic target cells have been removed from the
PVS and CNS, including the brain. However, in the absence of B target
cells in these tissues, there is no full activation of the cytotoxic T
cells. Therefore, less frequent neurological reactions could be observed
in said patient populations.

[0100] Accordingly, the absence of one of the above factors, in the
mentioned case the presence of target B cells in the PVS/CNS, could
possibly help to prevent neurological reactions. However, for example,
intrathecal chemotherapy is not the therapy of choice in NHL treatment.
For instance, it is not effective in indolent NHL therapy, and it is not
yet known whether it could be a treatment option for aggressive NHL. In
addition, intrathecal chemotherapy is highly toxic for ALL patients and
therefore associated with considerable health risks.

[0101] In light of the above, the depletion of any one of the above
indicated factors without loosing therapeutic efficacy is no trivial task
since it is for example not easily possible to avoid the presence of B
cells in the PVS/CNS of NHL. Furthermore, it has also been found that
other measures, including the pre- or co-administration of high doses of
steroids could not prevent neurological reactions in the high risk
patients.

[0102] However, by way of applying the methods/dosage regimens of the
present invention, it is possible to ameliorate and/or prevent adverse
effects for patients who are at an increased risk of such adverse effects
if they have a B:T cell ratio of about 1:5 or lower. The present
invention envisages providing dosage regimens (methods) which are even
independent of the above mentioned factors that could influence a
treatment with a CD19×CD3 bispecific antibody.

[0103] Thus, the present invention in a preferred aspect relates to a
method for assessing (analyzing) the risk of potential adverse effects
for a human patient mediated by the administration of a CD19×CD3
bispecific antibody to said patient comprising determining the ratio of B
cells to T cells determining in a sample from said patient, wherein a
ratio of about 1:5 or lower is indicative for a risk of potential adverse
effects for said patient, wherein said patient is

[0104] (a) administered a first dose of said antibody for a first period
of time; and is consecutively

[0105] (b) administered a second dose of said antibody for a second period
of time; wherein said second dose exceeds said first dose;

for

[0106] (i) treating malignant CD19 positive lymphocytes; and/or

[0107] (ii) for ameliorating and/or preventing an adverse effect mediated
by the administration of a CD19×CD3 bispecific antibody.

[0108] Preferably, in this preferred aspect, the patient is administered a
third dose of said antibody for a third period of time as described in
herein below. Accordingly, the embodiments and aspects described herein
in the context of the three-stage method (dose regimen) are applicable to
this preferred aspect.

[0109] In one aspect of the methods of the present invention said second
period of time exceeds said first period of time. The term "exceeds"
means that the second period of time is at least one day longer than the
first period of time.

[0110] Each of the methods (dosage regimens) of the present invention can
be repeated, for example, for one, two, three, four, five, six, or more
times and in any event as often as there is a beneficial effect for a
patient in ameliorating and/or treating malignant CD19 positive
lymphocytes, thereby treating lymphoma or leukemia. Dependent on the
ratio of the B:T cell ratio of a patient, in accordance with the teaching
of the present invention the practitioner can decide as to whether the
patient has to be "adapted" to a further treatment with a CD19×CD3
bispecific antibody prior by applying the dosage regimens of the present
invention (i.e., administering a low dose of a CD19×CD3 bispecific
antibody prior to administering a higher dose in order to "adapt" the
patient).

[0111] It must be understood that the dose or day ranges given herein are
illustrated by increments of one, two, three, four or five. These ranges,
however, in case of increments higher than one also encompass smaller
increments, for example those exemplified by increments of one (10 to 30
includes for example 10, 11, 12, 13, 13 etc. up to 30), or still smaller
increments, for example values after the decimal point.

[0112] In another aspect of the present invention, it is envisaged that
said first period of time is at least 3 days long, whereby even longer
periods of time of for example 8, 9, 10, 11, 12, 13 or 14 days are not
excluded. "Longer" is thereby not limited to a (one) complete day as the
lowest time unit, i.e. 1/2 days, or fully hours are also conceivable. It
is however preferred that the smallest time unit is one full day.

[0113] Accordingly, said first period of time exceeds 3 days. More
preferably, it is envisaged that said first period of time is between 3
days and 10 days, with 7 days being particularly preferred.

[0114] As used herein, a time interval which is defined as "X to Y"
equates with a time interval which is defined as "between X and Y". Both
time intervals specifically include the upper limit and also the lower
limit. This means that for example a time interval "3 to 10 days" or
between "3 to 10 days" includes a period of time of one, two, three,
four, five, six, seven and/or eight days.

[0115] As mentioned herein, the inventors observed that "adapting" a human
patient having a B:T cell ratio of about 1:5 or lower to the treatment
with a CD19×CD3 bispecific antibody during a first period of time
allows the treatment of the human patient with an increased second dose
of the antibody for a second period of time, whereby adverse effects (in
particular neurological reactions) can be better controlled, i.e., could
be avoided or at least kept within an acceptable grade in accordance with
the CTCAE.

[0116] However, for achieving this improvement it is required to "adapt"
the human patient having a B:T cell ratio of about 1:5 or lower to the
CD19×CD3 bispecific antibody by administering a first dose of the
antibody for a first period of time (wherein said first dose is lower
than the consecutive (second) dose). The administration can be a bolus
injection or a continuous administration, whereby a continuous
administration is preferred.

[0117] Likewise the duration of the first period of time, the duration of
the second period of time may be variable in view of, for example, the
age, sex, body weight, etc. of the human patient.

[0118] Accordingly, in another aspect of the present invention, it is
envisaged that said second period of time is at least 18 days long,
whereby even longer periods of time of for example 19, 20, 25, 30, 35,
40, 45, 49, 50, 55, 60, 65, 60, 65, 70, 75, 80, 81, 82, 83, 84, 85, 86,
87, 88 or 90 days are not excluded. "Longer" is thereby not limited to a
(one) complete day as the lowest time unit, i.e. 1/2 days, or fully hours
are also conceivable. It is however preferred that the smallest time unit
is one full day.

[0119] Accordingly, said second period of time exceeds 18 days. More
preferably, it is envisaged that said second period of time is between 18
days and 81 days, with 21 or 49 days being particularly preferred.

[0120] As used herein, a time interval which is defined as "X to Y"
equates with a time interval which is defined as "between X and Y". Both
time intervals specifically include the upper limit and also the lower
limit. This means that for example a time interval "18 to 81 days" or
between "18 to 81 days" includes a period of time of 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26,
27, 28, 29, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58,
60, 61, 62, 63 and/or 64 days.

[0121] In a more preferred embodiment of the methods/dosage regimens of
the present invention, said first period of time is between 3 days and 10
days, and said second period of time is between 18 and 81 days.

[0122] In an even more preferred embodiment, said first period of time is
7 days and said second period of time is 21 or 49 days.

[0123] In the clinical trials mentioned herein, it was observed that a
dose of 15 μg/m2/d in the treatment of NHL effected tumor
shrinkage as could be visualized in computer tomography. It was also
observed that a dose of 15 μg/m2/d in the treatment of ALL
resulted in minimal residual disease and could even eliminate MRD.

[0124] Minimal residual disease (MRD) is the name given, to small numbers
of leukemic/lymphoma cells that remain in the patient during treatment or
after treatment when the patient is in remission (no symptoms or signs of
disease). Up until a decade ago none of the tests used to assess/detect
cancer, were sensitive enough to detect MRD. Now, however, very sensitive
molecular biology tests are available--based on DNA, RNA or Proteins--and
these can measure minute levels of cancer cells in tissue samples,
sometimes as low as 1 cancer cell in million normal cells.

[0125] In cancer treatment, particularly leukaemia, MRD testing has
several important roles: determining whether treatment has eradicated the
cancer or whether traces remain, comparing the efficacy of different
treatments, monitoring patient remission status and recurrence of the
leukemia or cancer and choosing the treatment that will best meet those
needs (personalization of treatment)

[0126] Accordingly, in a further aspect of the methods/dosage regimens of
the present invention, said first dose is between 1 and 15
μg/m2/d, i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
μg/m2/d. Particularly preferred is a dose of 5 or 15
μg/m2/d.

[0127] As used herein, a dose interval which is defined as "between X and
Y" equates with a dose interval which is defined as "X to Y". Both dose
intervals specifically include the upper limit and also the lower limit.
This means that for example a dose interval "between 1 and 15" or "1 to
15" includes a dose of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
pg/m2/d.

[0128] "d" denotes one day.

[0129] "m2" denotes a square meter of a patient's body surface (BSA).
The "normal" average BSA is generally taken to be about 1.73 m2 for
an adult, for a neonate it is about 0.25 m2, for a 2 year old child
it is about 0.5 m2, for a 9 year old child it is about 1.07 m2,
for a 10 year old child it is about 1.14 m2, for a 12-13 year old
child it is about 1.33 m2, for men it is about 1.9 m2 and for
women it is about 1.6 m2.

[0130] However, the BSA can also be calculated more precisely by one of
the following formulas (each of these formulas can be applied when
calculating the BSA): [0131] The Mosteller formula (Mosteller, N Engl J
Med 1987 Oct. 22; 317(17): 1098):

[0131] BSA(m2)=([Height(cm)×Weight(kg)]/3600)1/2 or in
inches and pounds:

[0136] The term "μg" includes "μg of the CD19×CD3 bispecific
antibody preparation". It is preferred that not more than 10% of said
CD19×CD3 bispecific antibody preparation is incorrectly folded. It
follows that in a preferred embodiment, 90%, 91%, 92%, 93%, 94%, 95%,
96%, 97%, 98%, 99% or even 100% of the CD19×CD3 bispecific antibody
is correctly folded. It is also conceivable that the antibody preparation
may optionally comprise further ingredients, for example a lyoprotectant,
a surfactant, a filler, a binder, and/or bulking agent etc. The amount of
such further ingredients is, preferably, not included in the term "μg"
as used in the context of the "dose" and/or methods (dosage regimens) of
the present invention.

[0137] A dose of, for example, 1 μg/m2/d means that 1 μg of the
CD19×CD3 bispecific antibody is administered evenly or continuously
across one day per square meter body surface. "Continuously across one
day" refers to an infusion which is allowed to proceed permanently
without interruption.

[0138] In a further aspect of the methods/dosage regimen of the present
invention, said second dose is between 15 and 60 or 15 and 90
μg/m2/d, i.e. 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60
μg/m2/d or 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, 80 and 90
μg/m2/d. Particularly preferred is a dose of 60 or 90
μg/m2/d. Said second dose is thus therapeutically active.

[0139] In a preferred embodiment, said first dose is between 5 and 15
μg/m2/d and said second dose is between 15 and 60 or 15 and 90
μg/m2/d.

[0141] It must be understood that the ranges given herein are illustrated
by increments of five. These ranges, however, also encompass smaller
increments, for example those exemplified by increments of one (10 to 30
includes for example 10, 11, 12, 13, 13 etc. up to 30), or still smaller
increments, for example values after the decimal point.

[0142] Preferably, not included in the methods for administering a
CD19×CD3 bispecific antibody, for treating malignant CD19 positive
lymphocytes, or for ameliorating and/or preventing an adverse effect
mediated by the administration of a CD19×CD3 bispecific antibody
are the following administration schemes:

[0143] (i) 5 μg/m2 of the bispecific antibody for one day followed
by administration of 15 μg/m2 as daily dose for the remaining
period (second and each further consecutive day); and/or

[0144] (ii) 15 μg/m2 of the bispecific antibody for one day
followed by administration of 45 μg/m2 as daily dose for the
remaining period (second and each further consecutive day); and/or

[0145] (iii) 5 μg/m2 of the bispecific antibody for one day
followed by administration of 15 μg/m2 for one day, followed by
administration of 45 μg/m2 as daily dose for the remaining period
(third and each further consecutive day); and/or

[0146] (iv) less than 10-80 μg/m2 of the bispecific antibody for
one day followed by administration of a dose of 10-80 μg/m2
(second and each further consecutive day); and/or

[0147] (v) less than 10-80 μg/m2 of the bispecific antibody for
one day followed by administration of a dose of less 10-80 μg/m2
for one day, followed by administration of a dose of less 10-80
μg/m2 (third and each further consecutive day).

[0148] As mentioned herein, patients having a B:T cell ratio higher than
1:5, do not necessarily have to be adapted to the treatment with a
CD19×CD3 bispecific antibody by way of the dosage regimen of the
present invention. These patients having a decreased risk of potential
adverse effects could be treated by administration of a CD19×CD3
bispecific antibody in a constant dose of 5 μg to 75 μg per square
meter body surface area per day for at least four weeks. The
administration is preferably a continuous administration.

[0149] In another embodiment of the methods (dosage regimen) of the
present application, said methods further comprise administering after a
first and second dose for a first and second period of time a third dose
of said antibody for a third period of time. Accordingly, the present
invention provides a three-stage method (dosage regimen).

[0150] The administration of said third dose is intravenously. It can be
administered in the form of a bolus injection or continuously, with
continuously being preferred.

[0151] In one aspect of the methods of the present invention said third
period of time exceeds said first and second period of time. The term
"exceeds" means that the third period of time is at least one day longer
than the first and second period of time.

[0152] Likewise the duration of the first and second period of time, the
duration of the third period of time may be variable in view of, for
example, the age, sex, body weight, etc. of the human patient.

[0153] In the three-stage dosage regimen aspect of the present invention,
it is envisaged that said first period of time is at least 3 days long,
whereby even longer periods of time of for example 8, 9, 10, 11, 12, 13
or 14 days are not excluded. "Longer" is thereby not limited to a (one)
complete day as the lowest time unit, i.e. 1/2 days, or fully hours are
also conceivable. It is however preferred that the smallest time unit is
one full day.

[0154] Accordingly, said first period of time exceeds 3 days. More
preferably, it is envisaged that said first period of time is between 3
days and 10 days, with 7 days being particularly preferred.

[0155] As used herein, a time interval which is defined as "X to Y"
equates with a time interval which is defined as "between X and Y". Both
time intervals specifically include the upper limit and also the lower
limit. This means that for example a time interval "3 to 10 days" or
between "3 to 10 days" includes a period of time of one, two, three,
four, five, six, seven and/or eight days.

[0156] In the three-stage dosage regimen aspect of the present invention,
it is envisaged that said second period of time is at least 3 days long,
whereby even longer periods of time of for example 8, 9, 10, 11, 12, 13
or 14 days are not excluded. "Longer" is thereby not limited to a (one)
complete day as the lowest time unit, i.e. 1/2 days, or fully hours are
also conceivable. It is however preferred that the smallest time unit is
one full day.

[0157] Accordingly, said first period of time exceeds 3 days. More
preferably, it is envisaged that said first period of time is between 3
days and 10 days, with 7 days being particularly preferred.

[0158] As used herein, a time interval which is defined as "X to Y"
equates with a time interval which is defined as "between X and Y". Both
time intervals specifically include the upper limit and also the lower
limit. This means that for example a time interval "3 to 10 days" or
between "3 to 10 days" includes a period of time of one, two, three,
four, five, six, seven and/or eight days.

[0159] In the three-stage dosage regimen aspect of the present invention,
it is envisaged that said third period of time is at least 8 days long,
whereby even longer periods of time of for example 8, 9, 10, 11, 12, 13,
14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 32,
34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 61, 62, 63, 64,
65, 66, 67, 68, 69, 70 and/or 71 days are not excluded. "Longer" is
thereby not limited to a (one) complete day as the lowest time unit, i.e.
1/2 days, or fully hours are also conceivable. It is however preferred
that the smallest time unit is one full day.

[0160] Accordingly, said first period of time exceeds 8 days. More
preferably, it is envisaged that said first period of time is between 8
days and 78 days, with 14 or 42 days being particularly preferred.

[0161] As used herein, a time interval which is defined as "X to Y"
equates with a time interval which is defined as "between X and Y". Both
time intervals specifically include the upper limit and also the lower
limit. This means that for example a time interval "18 to 78 days" or
between "18 to 78 days" includes a period of time of 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26,
27, 28, 29, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58,
60, 61, 62 63, 64, 65, 66, 67, 68, 69, 70 and/or 71 days.

[0162] In a more preferred embodiment of the three-stage methods/dosage
regimens of the present invention, said first period of time is between 3
days and 10 days, and said second period of time is between 3 days and 10
days, and said third period of time is between 8 days and 78 days.

[0163] In an even more preferred embodiment, said first period of time is
7 days, said second period of time is 7 days, and said third period of
time is 14 or 42 days.

[0164] In an embodiment of the three-stage methods/dosage regimens of the
present invention, said third dose exceeds said first and second dose.
Said second and third dose are preferably therapeutically active. Of
note, said second dose exceeds said first dose.

[0165] Accordingly, in a further aspect of the three-stage methods/dosage
regimens of the present invention, said first dose is between 1 and 15
μg/m2/d, preferably between 5 and 15 μg/m2/d, i.e. 1, 2,
3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 μg/m2/d. Particularly
preferred is a dose of 5 or 10 μg/m2/d.

[0166] In a further aspect of the three-stage methods/dosage regimens of
the present invention, said second dose is between 1 and 15
μg/m2/d, preferably between 5 and 15 μg/m2/d, i.e. 1, 2, 3, 4,
5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 μg/m2/d. Particularly
preferred is a dose of 15 μg/m2/d.

[0167] As used herein, a dose interval which is defined as "between X and
Y" equates with a dose interval which is defined as "X to Y". Both dose
intervals specifically include the upper limit and also the lower limit.
This means that for example a dose interval "between 1 and 15" or "1 to
15" includes a dose of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
μg/m2/d.

[0168] In a further aspect of the three-stage methods/dosage regimen of
the present invention, said third dose is between 15 and 60
μg/m2/d, more preferably between 20 and 60 μg/m2/d, i.e.
15, 20, 25, 30, 35, 40, 45, 50, 55 and 60 μg/m2/d. Particularly
preferred is a dose of 60 μg/m2/d. Alternatively, said third dose
is between 15 and 90 μg/m2/d, more preferably between 60 and 90
μg/m2/d, i.e., 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, 80 and
90 μg/m2/d.

[0169] In a preferred embodiment of the three-stage methods/dosage regimen
of the present invention, said first dose is between 1 and 15
μg/m2/d, said second dose is between 1 and 15 μg/m2/d,
and said third dose is between 15 and 60 or 15 and 90 μg/m2/d.

[0170] Particularly preferred, said first dose is 5 μg/m2/d, said
second dose is 15 μg/m2/d, and said third dose is 60
μg/m2/d. Alternatively, said third dose may be 90
μg/m2/d.

[0172] In view of the observations made by the present inventors that a
three-stage (step) method/dosage regimen aids in avoiding adverse effects
as described herein, the present invention relates to a method of
treating malignant CD19 positive lymphocytes in a human patient, said
method comprising (a) administering a first dose of said antibody for a
first period of time; (b) administering a second dose of said antibody
for a second period of time; and consecutively (c) administering a third
dose of said antibody for a third period of time.

[0173] Also, the present invention relates to a method for treating
malignant CD19 positive lymphocytes in a human patient, said method
comprising (a) administering a first dose of said antibody for a first
period of time; (b) administering a second dose of said antibody for a
second period of time; and consecutively (c) administering a third dose
of said antibody for a third period of time.

[0174] Furthermore, the present invention relates to a method for
ameliorating and/or preventing an adverse effect mediated by the
administration of a CD19×CD3 bispecific antibody to a human
patient, said method comprising (a) administering a first dose of said
antibody for a first period of time; (b) administering a second dose of
said antibody for a second period of time; and consecutively (c)
administering a third dose of said antibody for a third period of time.

[0175] Preferably, the first, second and third period of time are as
described elsewhere herein.

[0176] Regarding the doses, it is preferred that the second dose exceeds
the first dose and the third dose exceeds the second dose as described
elsewhere herein. More preferably, the first dose is 5 μg/m2/d,
the second dose is 15 μg/m2/d and the third dose is 60
μg/m2/d. Alternatively, the third dose may also be 90 or 120
μg/m2/d.

[0177] As noted herein above, the present invention relates to methods of
treatment/dosage regimen which employ CD19×CD3 bispecific
antibodies, comprising a first binding domain capable of binding to an
epitope of human CD3 epsilon chain and a second binding domain capable of
binding to human CD19. Examples for bispecific molecules according to the
methods of the invention are described in great detail in WO 99/54440 and
WO 2004/106381 and WO 2008/119565. All the specific CD19×CD3
bispecific antibodies disclosed therein, including their variants,
fragments, equivalents etc. are particularly preferred CD19×CD3
bispecific antibodies of the present invention.

[0178] As used herein, a "CD19×CD3 bispecific antibody" (including a
CD19×CD3 bispecific single chain antibody) denotes a single
polypeptide chain comprising two binding domains. Such single chain
antibodies are preferred in the context of the methods/dosage regimen of
the present invention. Each binding domain comprises at least one
variable region from an antibody heavy chain ("VH or H region"), wherein
the VH region of the first binding domain specifically binds to the CD3
epsilon molecule, and the VH region of the second binding domain
specifically binds to CD19. The two binding domains are optionally linked
to one another by a short polypeptide spacer. A non-limiting example for
a polypeptide spacer is Gly-Gly-Gly-Gly-Ser (G-G-G-G-S) and repeats
thereof. Each binding domain may additionally comprise one variable
region from an antibody light chain ("VL or L region"), the VH region and
VL region within each of the first and second binding domains being
linked to one another via a polypeptide linker, for example of the type
disclosed and claimed in EP 623679 B1, but in any case long enough to
allow the VH region and VL region of the first binding domain and the VH
region and VL region of the second binding domain to pair with one
another such that, together, they are able to specifically bind to the
respective first and second binding domains. Such CD19CD3 bispecific
single chain antibodies are described in great detail in WO 99/54440 and
WO 2004/106381.

[0179] The term "binding domain" characterizes in connection with the
present invention a domain of a polypeptide which specifically binds
to/interacts with a given target structure/antigen/epitope. Thus, the
binding domain is an "antigen-interaction-site". The term
"antigen-interaction-site" defines, in accordance with the present
invention, a motif of a polypeptide, which is able to specifically
interact with a specific antigen or a specific group of antigens, e.g.
the identical antigen in different species. Said binding/interaction is
also understood to define a "specific recognition". The term
"specifically recognizing" means in accordance with this invention that
the antibody molecule is capable of specifically interacting with and/or
binding to at least two, preferably at least three, more preferably at
least four amino acids of an antigen, e.g. the human CD3 antigen as
defined herein. Such binding may be exemplified by the specificity of a
"lock-and-key-principle". Thus, specific motifs in the amino acid
sequence of the binding domain and the antigen bind to each other as a
result of their primary, secondary or tertiary structure as well as the
result of secondary modifications of said structure. The specific
interaction of the antigen-interaction-site with its specific antigen may
result as well in a simple binding of said site to the antigen. Moreover,
the specific interaction of the binding domain/antigen-interaction-site
with its specific antigen may alternatively result in the initiation of a
signal, e.g. due to the induction of a change of the conformation of the
antigen, an oligomerization of the antigen, etc. A preferred example of a
binding domain in line with the present invention is an antibody. The
binding domain may be a monoclonal or polyclonal antibody or derived from
a monoclonal or polyclonal antibody.

[0180] The term "antibody" comprises derivatives or functional fragments
thereof which still retain the binding specificity. Techniques for the
production of antibodies are well known in the art and described, e.g. in
Harlow and Lane "Antibodies, A Laboratory Manual", Cold Spring Harbor
Laboratory Press, 1988 and Harlow and Lane "Using Antibodies: A
Laboratory Manual" Cold Spring Harbor Laboratory Press, 1999. The term
"antibody" also comprises immunoglobulins (Ig's) of different classes
(i.e. IgA, IgG, IgM, IgD and IgE) and subclasses (such as IgG1, IgG2
etc.).

[0181] The definition of the term "antibody" also includes embodiments
such as chimeric, single chain and humanized antibodies, as well as
antibody fragments, like, inter alia, Fab fragments. Antibody fragments
or derivatives further comprise F(ab')2, Fv, scFv fragments or single
domain antibodies, single variable domain antibodies or immunoglobulin
single variable domain comprising merely one variable domain, which might
be VH or VL, that specifically bind to an antigen or epitope
independently of other V regions or domains; see, for example, Harlow and
Lane (1988) and (1999), cited above. Such immunoglobulin single variable
domain encompasses not only an isolated antibody single variable domain
polypeptide, but also larger polypeptides that comprise one or more
monomers of an antibody single variable domain polypeptide sequence.

[0182] As used herein, CD3 epsilon denotes a molecule expressed as part of
the T cell receptor and has the meaning as typically ascribed to it in
the prior art. In human, it encompasses in individual or independently
combined form all known CD3 subunits, for example CD3 epsilon, CD3 delta,
CD3 gamma, CD3 zeta, CD3 alpha and CD3 beta. The human CD3 epsilon is
indicated in GenBank Accession No. NM--000733.

[0200] It is more preferred that the CD19×CD3 bispecific antibody
applied in the methods of the present invention comprises the CD3 CDRs of
the heavy and light chain. Even more preferably, the CD19×CD3
bispecific antibody applied in the methods of the present invention
comprises the CD3 CDRs of the heavy and light chain as well as the CD19
CDRs of the heavy and light chain.

[0201] The CDRs referred to herein are in accordance with the Kabat
numbering system. The Kabat numbering scheme is a widely adopted standard
for numbering the residues in an antibody in a consistent manner (Kabat
et al., Sequences of Proteins of Immunological Interest, 1991).

[0202] Alternatively, it is preferred that the CD19×CD3 bispecific
antibody applied in the methods of the present invention comprises the

[0207] More preferably, the CD19×CD3 bispecific antibody applied in
the methods of the present invention comprises the CD19 variable heavy
and light chain and/or the CD3 variable heavy and light chain. Even more
preferably, the CD19×CD3 bispecific antibody applied in the methods
of the present invention comprises the CD19 variable heavy and light
chain as well as the CD3 variable heavy and light chain.

[0208] In another alternative, it is also preferred that said bispecific
single chain antibody comprises an amino acid sequence selected from the
group consisting of

[0211] (c) an amino acid sequence encoded by a nucleic acid sequence
having at least 70%, 80%, 90%, 95% or 99% identity to a nucleic acid
sequence of (b), wherein said amino acid sequence is capable of
specifically binding to CD3 and CD19; and

[0212] (d) an amino acid sequence encoded by a nucleic acid sequence which
is degenerate as a result of the genetic code to a nucleotide sequence of
(b), wherein said amino acid sequence is capable of specifically binding
to CD3 and CD19.

[0213] It is to be understood that the sequence identity is determined
over the entire amino acid sequence. For sequence alignments, for
example, the programs Gap or BestFit can be used (Needleman and Wunsch J.
Mol. Biol. 48 (1970), 443-453; Smith and Waterman, Adv. Appl. Math 2
(1981), 482-489), which is contained in the GCG software package
(Genetics Computer Group, 575 Science Drive, Madison, Wis., USA 53711
(1991). It is a routine method for those skilled in the art to determine
and identify an amino acid sequence having e.g. 70%, 80%, 90%, 95%, 96%,
97%, 98% or 99% sequence identity to the amino acid sequences of the
CD19xCD3 bispecific antibody described herein (preferably MT103). For
example, according to Crick's Wobble hypothesis, the 5' base on the
anti-codon is not as spatially confined as the other two bases, and could
thus have non-standard base pairing. Put in other words: the third
position in a codon triplet may vary so that two triplets which differ in
this third position may encode the same amino acid residue. Said
hypothesis is well known to the person skilled in the art (see e.g.
http://en.wikipedia.org/wiki/Wobble_Hypothesis; Crick, J Mol Biol 19
(1966): 548-55). It is furthermore a routine procedure for those skilled
in the art to determine cytotoxic activity of such an amino acid sequence
having e.g. 70%, 80%, 90%, 95%, 96%, 97%, 98% or 99% sequence identity to
the nucleotide or amino acid sequences of the CD19×CD3 bispecific
single chain antibody described herein. Cytotoxic activity of the
CD19×CD3 bispecific single chain antibody or an antibody construct
having e.g. 70%, 80%, 90%.sub., 9.sub.5%.sub., 96%, 97%, 98% or 99%
sequence identity to the amino acid sequences of the CD19×CD3
bispecific single chain antibody can be determined by methods as
illustrated e.g. in WO 99/54440.

[0223] (iii) ameliorating or preventing an adverse effect mediated by the
administration of a CD19×CD3 bispecific antibody to a human
patient;

wherein said antibody is to be administered in accordance with a method
as defined in any one of the preceding claims.

[0224] In a further aspect, the present invention concerns the use of a
CD19×CD3 bispecific antibody for the preparation of a
pharmaceutical composition to be used in a method as defined in any one
of the preceding claims.

[0225] The pharmaceutical composition of the present invention may
optionally comprise a pharmaceutical carrier. Examples of suitable
pharmaceutical carriers are well known in the art and include phosphate
buffered saline solutions, sterile solutions etc. Intravenous vehicles
include fluid and nutrient replenishers, electrolyte replenishers (such
as those based on Ringer's dextrose), and the like. Preservatives and
other additives may also be present such as, for example, antimicrobials,
anti-oxidants, chelating agents, and inert gases and the like.
Furthermore, the pharmaceutical composition of the invention may comprise
further agents such as chemotherapeutic agents as explained herein
elsewhere.

[0226] In a further aspect, the present invention relates to a
(pharmaceutical) kit or pharmaceutical package comprising the first dose
and the second dose as defined herein.

[0227] In another embodiment, the present invention relates to a
(pharmaceutical) kit or pharmaceutical package comprising the first dose
and the second dose as defined herein as well as the third dose as
defined in the context of the three-stage dosage regimen/method.

[0228] In another aspect, the (pharmaceutical) kit or pharmaceutical
package comprises all three doses as defined herein in the context of the
three-stage dosage regimen/method, i.e., the first, the second and the
third dose.

[0229] Said first, second and third dose are thereby packaged together in
one sealed pharmaceutical package or kit. It will be understood that the
"first dose", the "second dose" and the "third dose" encompasses in this
regard the respective number of single doses which will be used for a
given period of time (either the first or the second period of time).
This means for example that the "first dose" or "second dose" which is
comprised in the pharmaceutical package or kit of the present invention
comprises, for example, 7 daily doses which are separated. The number of
packaged daily doses thereby reflects the intended period of time (X
daily doses if said period of time is X days, Y daily doses if the period
of time is Y days and so on). In these embodiments, the (pharmaceutical)
kit or pharmaceutical package comprises the daily dosages in separate
containers, in a single package.

[0230] Alternatively, it is also envisaged that the intended first dose
and/or second dose and/or third dose is not separated into the respective
number of daily doses but is contained, either in toto or in part, in one
single container (for example an infusion bag), which comprises the
required dose for either the first and/or the second period of time
either in part (for example for 1 to 3 days) or in toto (i.e. for the
first or second period of time). This means that one single container
comprises for example 7 daily doses for the "first dose" which is to be
used during the first period of time etc.

[0231] It will be understood that the (pharmaceutical) kit or
pharmaceutical package of the present invention may also comprises more
or less daily doses as required for the respective period of time (either
separated or not). Alternatively, the (pharmaceutical) kit or
pharmaceutical package is prepared such that it contains the required
number of daily doses (either separated or not) for the first and second
period of time as defined herein, i.e. the "first dose", the "second
dose" and the "third dose" in one single package. Such a package is
ideally sufficient for one complete treatment of a patient (including the
first and the second period of time). Parts of the kit and package of the
invention can be packaged individually in vials or bottles or in
combination in containers or multicontainer units. The manufacture of the
kits follows preferably standard procedures which are known to the person
skilled in the art.

[0232] Furthermore, the invention relates to a pharmaceutical package or
kit as described hereinbefore and written instructions for the sequential
use thereof in accordance with the methods of the present invention. Said
pharmaceutical package or kit may further comprise a label or imprint
indicating that the contents can be used for treating malignant CD19
positive lymphocytes present in lymphoma or leukemia in a human patient;
or for ameliorating or preventing an adverse effect mediated by the
administration of a CD19×CD3 bispecific antibody to a patient.

[0233] It is also envisaged that the pharmaceutical package or kit of the
present invention, further comprises means to administer the first and/or
the second dose and/or third dose to a patient and/or buffers, vials,
teflon bags or infusion bags which are normally used for the infusion of
therapeutic agents. "Means" thereby includes one or more article(s)
selected from the group consisting of a syringe, a hypodermic needle, a
cannula, a catheter, an infusion bag for intravenous administration,
intravenous vehicles, vials, buffers, stabilizers, written instructions
which aid the skilled person in the preparation of the respective doses
and infusions of the invention etc.

[0234] It is also envisaged that the pharmaceutical package or kit of the
present invention further comprises a chemotherapeutic agent.

[0235] In a further aspect, the present invention provides for a
pharmaceutical package or kit, wherein said first and/or said second dose
is arranged such, that it is suitable for (prepared for) administration
of a dosage regimen in accordance with a method of any one of the
preceding claims.

EXAMPLES

[0236] The following examples illustrate the invention. These examples
should not be construed as to limit the scope of this invention. The
examples are included for purposes of illustration and the present
invention is limited only by the claims.

Example 1

Identification of a Predictive Factor for Reversible Neurological Adverse
Events in a Subset of Non-Hodgkin Lymphoma Patients Treated with
CD19-Specific BiTE Antibody Blinatumomab

[0237] Blinatumomab is a CD19/CD3-bispecific antibody construct of the
bispecific T cell engager (BiTE®) class showing as single agent a
high rate and duration of responses in patients with relapsed non-Hodgkin
lymphoma (NHL) and B-precursor acute lymphocytic leukemia (ALL).
Blinatumomab has a favorable safety profile with exception of a subset of
patients developing neurological adverse events (AEs) during the first
days of treatment, such as confusion, speech impairment or cerebellar
symptoms. Thus far, all relevant neurological AEs (11 out of 48 patients)
were transient, fully reversible and resolved without sequelae within 3
to 72 hours after stop of infusion. In no case, pathological findings
were seen upon cranial magnetic resonance imaging. Despite treatment
discontinuation, 4 patients with neurological AEs have achieved an
objective lymphoma remission. Analysis of cerebrospinal fluid (CSF) taken
within hours after stop of infusion showed detectable levels of
blinatumomab in the majority of affected patients, while in one patient
without neurological symptoms no blinatumomab was detectable in CSF
during infusion. Moreover, increased levels of albumin and T lymphocytes
in CSF support a disturbance of the blood brain barrier (BBB) as a
possible underlying event. Analyses of patient serum samples for
angiopoetin-2 and S100β are ongoing to investigate whether levels of
the endothelial stress and BBB integrity marker, respectively, correlate
with neurological AEs. In a retrospective analysis of 39 NHL patients, a
baseline B cell to T cell (B:T) ratio in peripheral blood at or below
1:10 was identified as the only predictive factor for the subsequent
occurrence of neurological AEs. The predictive value was then
prospectively confirmed in 8 additional patients. Of note, ALL
patients--despite very low B:T ratios--rarely showed neurological AEs,
which may relate to previous intrathecal chemotherapy depleting target
cells in the brain. Potential mechanisms for the neuroprotective effect
of peripheral B cells are being investigated. In conclusion, we
identified a simple measure to prospectively identify patients at risk of
developing neurological AEs after onset of blinatumomab treatment.
Mitigating measures are currently tested in these high-risk patients in
order to avoid discontinuation of treatment.

Example 2

Synopsis of Observations (1) in Patients Treated with a CD19×CD3
Bispecific Antibody

[0243] Features of CNS Events with Slow Onset [0244] Biased to
cerebellar symptoms [0245] Occur at various time points during treatment,
frequently at beginning of treatment or at step increase [0246] Tremor,
mild speech impairment, mild writing impairment; can last for several
days